Many claims that uplift of the Qinghai‐Tibetan plateau (QTP) drove the divergences of extant high‐elevation biota have recently been challenged. For Mendacibombus bumblebees, high‐elevation ...specialists with distributions centred on the QTP, we examine broader explanations. We extend integrative biogeography to cover multiple contributing factors by using a framework of sequential filters: 1) molecular evidence from four genes is used to estimate phylogenetic relationships, with time calibration from a published estimate; 2) spatial evidence from current distributions is combined with the phylogeny and constrained by a model of short‐distance dispersal along mountain corridors to estimate ancestral distributions by both S‐DIVA and S‐DEC analysis; 3) geological evidence from the literature is used to constrain when high mountain ranges were uplifted to become potential corridors; and 4) climatological evidence from Mendacibombus niche‐evolution reconstructions and from palaeoclimate simulations is used to constrain when habitat was suitable in key gaps within corridors. Explanations for Mendacibombus distributions can be identified that require only short‐distance dispersal along mountain corridors, commensurate with the limited dispersal ability observed for bumblebees. These explanations depend on the timing of uplift of mountain ranges, regional climate change, and climate‐niche evolution. The uplift of the QTP may have contributed to the initial Oligocene divergence of the common ancestor of Mendacibombus from other bumblebees, but for the first two thirds of the history of Mendacibombus, only a single lineage has present‐day descendants. Divergence of multiple extant Mendacibombus lineages coincided with the Late Miocene–Pliocene uplift of externally connecting mountains, combined with regional climate cooling. These changes provided greater connectivity of suitable habitat, allowing these bumblebees to disperse out of the western QTP via new high bridges, escaping along the mountain corridors of the Tian Shan and Hindu Kush ranges, reaching eventually far to the west (Iberian Peninsula) and to the north‐east (Kamchatka).
In the last decade, the application of predictive models of species distribution in ecology, evolution, and conservation biology has increased dramatically. However, limited available data and the ...lack of reliable absence data have become a major challenge to overcome. At least two approaches have been proposed to generate pseudo-absences; however it is not clear how the number of pseudo-absences created affect model performance. Moreover, the spatial bias in the collecting localities of a species (presence data) may add extra noise to the final distribution model. Here, we use a virtual species to assess the effects of spatial sampling bias, and number and location of pseudo-absences on model accuracy. We found that both number of pseudo-absences and spatial bias in sampling localities, as well as their interaction, significantly influence all accuracy measures (AUC, sensitivity, and specificity). However, location of pseudo-absences (either generated across the entire study area or only outside the environmental envelope of the species) does not affect model performance. These results provide some methodological guidelines for developing reliable distribution hypotheses when presence data are scarce.
The altitudinal gradient in diversity of dung beetles (Scarabaeidae) was studied in a Mediterranean mountain chain located in Central Anatolia to (i) determine if there are altitudinal differences ...between the main taxonomic groups, (ii) describe the seasonal variations in these assemblages and (iii) assess whether closed habitats influence dung beetle diversity differentially at different altitudes. Beetles were collected throughout a year at 14 localities between 469 and 1810 m above sea level in three different types of habitats. Dung beetle assemblages at 400 to 1200 m did not vary greatly in species richness, abundance and biomass. However, they varied in composition, with the assemblages dominated by species of Scarabaeinae up to 900 m, whereas in the mid-mountain assemblages (from 900 m to 1600 m) the numbers of species of Aphodiinae was higher. The decline with increase in altitude in richness, abundance and biomass of both small and large species of Scarabaeinae up to 1500 m, together with the constancy of these parameters in the case of Aphodiinae, accounts for the changes in the composition from the lowland to mid-mountain localities. Unlike at other Mediterranean localities, the open/closed structure of the habitat only slightly infl uences these assemblages independently of altitude or season. The general seasonal pattern follows the classical Mediterranean bimodal pattern associated with summer drought, but the patterns are more complex when the seasonal responses of the different groups and at different localities are analysed separately. We propose that the interplay between local climatic conditions (mainly temperature) and evolutionary conserved species preferences accounts for both the current seasonal and altitudinal gradients and the changes in species composition in terms of Aphodiinae and Scarabaeinae.
Knowing how recent environmental changes may have affected species diversity is a major objective to estimate the consequences of habitat alteration and climate change. In this study two dung beetle ...inventories made in the same locality of the Sierra de Guadarrama (Madrid, Spain) 34 years apart (1983–2017) are compared. Changes in diversity, species richness, abundances and composition were analysed and species replacements described considering the three main functional dung beetle groups: large paracoprids, small paracoprids and small endocoprids. In addition, changes in vegetation cover and climate between the two periods were also analysed to examine their association with the detected faunistic changes. Both the vegetation and climatic data show that the surveyed locality would have experienced an increase in the area covered by bushes and forest and an increase in temperature and warm conditions during the 34 years. These changes are associated with a probable increase in species richness and species dominance, a decrease in diversity and an important change in composition that would have positively affected small paracoprids but negatively affected large paracoprids.
Abstract
Estimating the realized and potential distribution of species has become a very active field of research with capacity to propose likely speciation mechanisms. Here, environmental variables ...and point locality data derived from several sources were used to examine the concordance between geographical distributions and environmental niches derived from occurrences for eleven species of the genus Uromastyx (Reptilia, Agamidae). Our results indicate that the degree of geographical overlap is definitively and statistically lower than the degree of environmental similarity. This reinforces the hypothesis that speciation process within the genus Uromastyx will be mainly based on geographical isolation. However, the environmental divergence among some groups of species cannot be excluded; high environmental distances can be obtained for some related species and the environmental gradient represented by two unique climatic variables allows discriminating some species among which an ecological or environmental segregation would be a plausible explanation.
•Biodiversity research often requires discriminating well-surveyed spatial units.•An application (KnowBR) directed to estimate the completeness of species inventories is presented.•KnowBR can ...simultaneously work across an unlimited number of spatial units and extents.
Biodiversity databases are typically incomplete and biased. We identify their three main limitations for characterizing the geographic distributions of species: unknown levels of survey effort, unknown absences of a species from a region, and unknown level of repeated occurrence of a species in different samples collected at the same location. These limitations hinder our ability to distinguish between the actual absence of a species at a given location and its (erroneous) apparent absence as consequence of inadequate surveys. Good practice in biodiversity research requires knowledge of the number, location and degree of completeness of relatively well-surveyed inventories within territorial units. We herein present KnowBR, an application designed to simultaneously estimate the completeness of species inventories across an unlimited number of spatial units and different geographical extents, resolutions and unit expanses from any biodiversity database. We use the number of database records gathered in a territorial unit as a surrogate of survey effort, assuming that such number correlates positively with the probability of recording a species within such area. Consequently, KnowBR uses a “record-by-species” matrix to estimate the relationship between the accumulated number of species and the number of database records to characterize the degree of completeness of the surveys. The final slope of the species accumulation curves and completeness percentages are used to discriminate and map well-surveyed territorial units according to user criteria. The capacity and possibilities of KnowBR are demonstrated through two examples derived from data of varying geographic extent and numbers of records. Further, we identify the main advances that would improve the current functionality of KnowBR.
Among macrocyclic lactones (ML), ivermectin (IVM) and moxidectin (MOX) potentially affect all Ecdysozoan species, with dung beetles being particularly sensitive. The comparative effects of IVM and ...MOX on adult dung beetles were assessed for the first time to determine both the physiological sub-lethal symptoms and pre-lethal consequences. Inhibition of antennal response and ataxia were tested as two intuitive and ecologically relevant parameters by obtaining the lowest observed effect concentration (LOEC) values and interpolating other relevant toxicity thresholds derived from concentration-response curves (IC
, as the concentration of each ML where the antennal response is inhibited by half; and pLC
, as the quantity of ingested ML where partial paralysis was observed by half of treated individuals) from concentration-response curves. Both sub-lethal and pre-lethal symptoms obtained in this study coincided in that IVM was six times more toxic than MOX for adult dung beetles. Values of LOEC, IC
and pLC
obtained for IVM and MOX evaluated in an environmental context indicate that MOX, despite needing more time for tis elimination in the faeces, would be twice as harmful to dung beetles as IVM. This approach will be valuable to clarify the real impact of MLs on dung beetle health and to avoid the subsequent environmental consequences.
Human-caused disturbances can lead to the extinction of indigenous (endemic and native) species, while facilitating and increasing the colonisation of exotic species; this increase can, in turn, ...promote the similarity of species compositions between sites if human-disturbed sites are consistently invaded by a regionally species-poor pool of exotic species. In this study, we analysed the extent to which epigean arthropod assemblages of four islands of the Azorean archipelago are characterised by nestedness according to a habitat-altered gradient. The degree of nestedness represents the extent to which less ubiquitous species occur in subsets of sites occupied by the more widespread species, resulting in an ordered loss/gain of species across environmental or ecological gradients. A predictable loss of species across communities while maintaining others may lead to more similar communities (i.e. lower beta-diversity). In contrast, anti-nestedness occurs when different species tend to occupy distinct sites, thus characterising a replacement of species across such gradients. Our results showed that an increase in exotic species does not promote assemblage homogenisation at the habitat level. On the contrary, exotic species were revealed as habitat specialists that constitute new and well-differentiated assemblages, even increasing the species compositional heterogeneity within human-altered landscapes. Therefore, contrary to expectations, our results show that both indigenous and exotic species established idiosyncratic assemblages within habitats and islands. We suggest that both the historical extinction of indigenous species in disturbed habitats and the habitat-specialised character of some exotic invasions have contributed to the construction of current assemblages.
Ivermectin is a veterinary pharmaceutical generally used to control the ecto- and endoparasites of livestock, but its use has resulted in adverse effects on coprophilous insects, causing population ...decline and biodiversity loss. There is currently no information regarding the direct effects of ivermectin on dung beetle physiology and behaviour. Here, based on electroantennography and spontaneous muscle force tests, we show sub-lethal disorders caused by ivermectin in sensory and locomotor systems of Scarabaeus cicatricosus, a key dung beetle species in Mediterranean ecosystems. Our findings show that ivermectin decreases the olfactory and locomotor capacity of dung beetles, preventing them from performing basic biological activities. These effects are observed at concentrations lower than those usually measured in the dung of treated livestock. Taking into account that ivermectin acts on both glutamate-gated and GABA-gated chloride ion channels of nerve and muscle cells, we predict that ivermectin's effects at the physiological level could influence many members of the dung pat community. The results indicate that the decline of dung beetle populations could be related to the harmful effects of chemical contamination in the dung.
The process of seed dispersal of many animal-dispersed plants is frequently mediated by a small set of biotic agents. However, the contribution that each of these dispersers makes to the overall ...recruitment may differ largely, with important ecological and management implications for the population viability and dynamics of the species implied in these interactions. In this paper, we compared the relative contribution of two local guilds of scatter-hoarding animals with contrasting metabolic requirements and foraging behaviours (rodents and dung beetles) to the overall recruitment of two Quercus species co-occurring in the forests of southern Spain. For this purpose, we considered not only the quantity of dispersed seeds but also the quality of the seed dispersal process. The suitability for recruitment of the microhabitats where the seeds were deposited was evaluated in a multi-stage demographic approach. The highest rates of seed handling and predation occurred in those microhabitats located under shrubs, mostly due to the foraging activity of rodents. However, the probability of a seed being successfully cached was higher in microhabitats located beneath a tree canopy as a result of the feeding behaviour of beetles. Rodents and beetles showed remarkable differences in their effectiveness as local acorn dispersers. Quantitatively, rodents were much more important than beetles because they dispersed the vast majority of acorns. However, they were qualitatively less effective because they consumed a high proportion of them (over 95%), and seeds were mostly dispersed under shrubs, a less suitable microhabitat for short-term recruitment of the two oak species. Our findings demonstrate that certain species of dung beetles (such as Thorectes lusitanicus), despite being quantitatively less important than rodents, can act as effective local seed dispersers of Mediterranean oak species. Changes in the abundance of beetle populations could thus have profound implications for oak recruitment and community dynamics.
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